Drying apparatus



B. OFFEN 2,297,314

DRYING APPARATUS Filed March 4, 1939 Sept. 29, 1942.

s Sheets-Sheet i INVENTOR Zen/Zara Q em B'Y pg ATTO R N EY Sept. 29,1942. B. oFFEN 2,297,314

" DRYING APPARATUS Filed March 4, 1939 3 Sheets-Sheet 2 INVENTOR Berna/dWe ATTORNEY Sept. 29, 1942. I B. OFFEN 7,

' DRYING APPARATUS Filed March 4 1939 3 Sheets-Sheet 3 INVES fiermzr' 0an n ATTORNEY Patented Sept. 29, 1942 UNITED STATES PATENT OFFICE DRYINGAPPARATUS Bernard Offen, Chicago, Ill.

Application March 4, 1939, Serial No. 259,743

6 Claims.

This invention relates to drying, and more particularly, to the dryingof web materials such as paper, textiles, metal plating, foils, and thelike.

The general object of the invention is to provid an improved apparatusfor drying various types of web materials, which enable the necessarydrying to be accomplished more quickly and economically than heretofore.

It is another object of the invention to provide apparatus for dryingweb materials, such as freshly printed paper or the like, which utilizerelatively high temperatures but which insure against scorching of orsimilar damage to such materials. Th high temperatures employed make forrapid and effective drying action, but are at all times prevented fromadversely affecting the material being dried.

It is another object of the invention to provide a drying system inwhich gas burners or the like are employed within an insulated dryinghood or chamber through which the material to be dried is assed, theflames from said burners serving to hea to a relatively high temperatureair which is passed to said material for contact therewith, the flamesthemselves being out of contact with said material. In this way, thetemperature of the drying air supplied to web material may be raised tothe order of 1500 F. or higher, if desired. This hot air, supplied tothe material at a suitably high velocity, sweeps the vapors from thematerial and thus brings about rapid and effective drying.

It is another object of the invention to provid a heating system inwhich material to be dried is passed through a drying chamber and iscontacted by hot air, a great portion Of which is normally recirculatedto the chamber after contacting with the material, but substantially allof which is discharged and replaced by relatively cool air whenever thepassage of material through the chamber is interrupted. Thus, forexample, whenever the web passing through the chamber is halted,relatively cool air is supplied thereto at once to prevent scorching orburning which might otherwise occur due to the high temperature of thchamber interior, although normally a large percentage of the hot airwithdrawn from the drying chamber is recirculated thereto in theinterest of operating economy.

It is another object of the invention to provide a drying system fordrying web materials such as freshly-inked paper or the like, in whichsteam is employed to advantage in a plurality of ways, in conjunctionwith a hot air drying chamber through which such material is passed.Thus,

steam may be used to preheat the material as it passes to the chamber,may be used to facilitate heat transfer and thus increase theeffectiveness of the dryin air so as to permit the use of loweroperating temperatures, and may be used for re,- turning moisture to thmaterial as it leaves the drying chamber. The steam which is mixed withthe drying air in the chamber is withdrawn with such air from thechamber and is recirculated "to the chamber.

It is another object Of the invention to provide, in a drying systemincluding a drying chamber, a novel method of and means for generatingand/or superheating steam for use in such system. i

It is another object of the invention to provide a system for drying webmaterial or the lik in which heat is supplied to one side of thematerial while the other sid thereof is adjacent surfaces maintained ata temperature below the charring temperature of the web material.

It is another object of the invention to provide a drying systemincluding a drying chamber, in which leakage of vapors and fumes fromthe drying chamber into the ambient atmosphere is eifectively preventedat all times.

It is another object of the invention to provide a drying chamber havingone or more gas burners, the operation of which are controlled inresponse to variations in temperature within the chamber and in thespeed at which material to be dried is passed through the dryingchamber. Thus, in a preferred embodiment of the invention, five burnersare provided, and the number of these which are operated is varied inaccordance with the temperature within the drying chamber. Whenever thepassage of material through the chamber is interrupted, all of theburners are rendered inoperative, such control preferably beingautomatic rather than manual, so as to assure an adequately promptresponse.

It is another object of the invention to provide an apparatus for dryingweb materials which is compact and essentially self-contained, which maybe installed readily and in a short time; which is relatively simple;and which is reliable as well as effective and inexpensive to operate.

Other objects and features of the invention,

.and the particular constructions and combinations of parts employed,will be more apparent from the following description, to be read inconnection with the accompanying drawings in which:

Fig. l is a diagrammatic view, partly broken away and partly in section,of a drying apparatus I embodying the invention in a. preferred form,taken on the line l-l of Fig. 2;

Fig. 2 is a plan view, partly in section, of the apparatus of Fig. 1;

Fig. 3 is a longitudinal sectional view taken on the line 3-3 of Fig. 1;

Fig. 4 is a fragmentary view of a portion of the drying chamber, takensimilarly to Fig. 3, illustrating a modified construction.

Fig. 5 is a fragmentary view, similar to Fig. 4, illustrating anothermodified construction; and

Fig. 6 is a view taken'on the line 66 of Fig. 5.

Referring now to the drawings, the numeral 20 designates generally adrying chamber of relatively elongated configuration, as seen in Fig. 3,and of a width suflicient to accommodate web material or the like whichis to be passed therethrough. Because of the high temperatures whichnormally prevail within the chamber during the operation thereof, theinterior of the chamber is provided with an insulating lining 2|.

At one end of the chamber 20 and near the rear thereof there is providedan opening 22, through which the web material, designated 23, is adaptedto be supplied within the chamber. At the opposite end of the chamberthere is similarly provided an opening 24, through which the webmaterial is adapted to be delivered from the chamber'to rollers 25, oneor more of which may be cooled, as by maintaining a circulation of coldwater therethrough, in order to cool the web material 23 as it issuesfrom the chamber 20.

Within the chamber are positioned a plurality of baflie members 26extending thereacross. As best seen in Fig. 3, the bailles 26 aregenerally U-shaped in configuration, thus to provide a plurality ofalternately arranged air supply passages 21 and air return passages 28.At one side of the chamber there is provided an exhaust manifold chamber29 with which the air return passages 28 communicate through suitableopenings 30 in end plate 3|. A partition 32, together with plate 3!,segregates manifold chamber 29 from the remainder of the interior ofdryer chamber 30.

In the supply passages 21, spaced an appreciable distance from the web23 and preferably toward the front of chamber 20, and extending acrosschamber 20, are arranged a plurality of gas supply pipes 33, eachprovided with an outlet slot or the like 34, which preferably extendssubstantially throughout the length of the pipe. These slotted pipesconstitute burners, and each may be provided with conventional pilotlights (not shown) or the like, for igniting gas deliveredtherefrom. Thesupply of gas or other fuel to the burners may be controlled in anydesired manner. Preferably, however, the pipes are arranged in groupsfed by suitable supply manifolds. Thus, as illustrated, the upper threepipes receive fuel from supply line 35, through manifold 36, while thelower two pipes receive fuel from supply line 31, through manifold 38.

Each pipe 33 is provided with a. metallic shield or the like 39 which isarranged to extend on opposite sides of each flame in the direction ofthe flame and in the direction of air flow through the passages 21.While the flames are thus effective for heating the air deliveredthrough the passages 21, and may in operation extend beyond the ends ofthe shields, the slots 34 are protected from the force of this air, sothat the fuel delivered from the burners may burn smoothly and evenly.

It will be observed that all of the air supply passages except thebottom one are arranged to discharge air in a direction having acomponent counter to the direction in which the web travels. Thus, therelative velocity of the air with respect to the web is greater than itotherwise would be, and this tends to render the drying air moreeffective not only as regards heat transfer, but also from thestandpoint of breaking up the film of air which extends to form at thesurface of the web. The lowermost air passage 21 discharges somewhat inan upward direction so that this air may be exhausted through thelowermost exhaust passage 28, this arrangement being employed tominimize any opportunity for outward leakage through the opening 22.

An air circulating fan 40 draws fresh air from the outdoor atmosphere orany other desired source through connection 4|, and return air from duct42, and supplies this air, through supply duct 43, to the chamber 20through an opening 44. The air thus delivered within chamber 20 willpass through the supply passages 21, then contact with the web 23 toeffect drying thereof, then pass through exhaust passages 28and'openings 3D to the manifold chamber 29. Part of this air will thenpass through opening 45 to duct 42 and be recirculated. Another portionof the air from manifold chamber 29 will be withdrawn through opening 46and duct 41 by exhaust fan 48, and exhausted from the system throughexhaust duct 49. Whenever reference is made herein to recirculation ofair which has contacted the web, it is to be understood that both airand products of combustion are actually recirculated.

At the outlet end of the chamber 20 is formed an auxiliary exhaustchamber 50, into which there pass any gases or fumes which may escapefrom the chamber 20 through opening 24. Duct 5| provides communicationbetween chamber 50 and duct 41, so that such gases or fumes areexhausted from the system and prevented from entering the ambientatmosphere.

Air inlet connection 4| is provided with suitable dampers 52 forcontrolling air flow therethrough, and return duct 42 is similarlyequipped with dampers 53. The dampers 52 and 53 are differentiallyinterconnected, as by bell-crank 54, so that as dampers 52 open, dampers53 correspondingly close; and vice versa. Thus, while the volume of airdelivered to the drying chamber 20 by fan 40 remains constant, theproportions of fresh and return air may be varied in accordance withoperating requirements.

The exhaust duct 41 is also provided with a suitable damper, designated55, which is preferably linked to the bell-crank 54 or otherwisearranged to be adjusted in accordance with the settings of dampers 52and 53.

The positions of the dampers 52, 53 and 55 are adjusted in accordancewith the speed at which the web 23 is passed through the drying chamber20. Since various instrumentalities and arrangements for effecting suchoperation are well known, no detailed description thereof is deemedrequired here. For purposes of illustration, however, the bell-crank 54is shown to be under the control of a damper motor or the like 56, theoperation of which is controlled by a speed responsive control deviceindicated at 51, the connection between the control device 51 and dampermotor 55 being indicated by the dash line 58.

Under normal operating conditions, when the web 23 passes through thechamber 20 at relathe air delivered to return manifold chamber 29 willbe recirculated. Accordingly, the damper 55 will be relatively closed,so that the exhaust fan 48 handles only about twenty per cent of themaximum air volume it is capable of handling. Also, the dampers 53 areopen relatively wide, while fresh air dampers 52 are open but relativelyslightly. However, in the event the web is stopped, the dampers areimmediately adjusted to the position shown in Fig. 2. Thus, the exhaustdamper 55 is wide open, the fresh air dampers 52 are wide open, and therecirculated air dampers 53 are tightly closed. Thus relatively coolfresh air only is circulated in contact with the web, and scorchingthereof is avoided, despite the high temperature of the interior of thedrying chamber.

It is to be understood, further, that the system is so designed andoperated that at all times more air is exhausted through duct 49 than issupplied to the system through connection 4|. Thus, in accordance withthe teachings of my copending application, Serial No. 6453, filedFebruary 14, 1935, and issued as Patent No. 2,152,770, outward leakageof gases and fumes from the drying chamber into the ambient atmosphereis effectively prevented.

To control the burner operation in accordance with the speed of the weband to interrupt the burner operation when the web has stopped, the gassupply lines 35 and 31 are respectively provided with valves 59 and 60,underthe control of speed responsive control device 51, through controllines or the like diagrammatically indicates at 58a. Since variouscontrol devices of this nature are well known in the art, no detaileddescription thereof is deemed necessary. If desired, the gas supplylines 35 and 31 may be provided respectively with manual shut-off valvesBI and 62.

To maintain desired regulation of the temperature within the dryingchamber 20, there is provided a thermostat 63 extending within the frontportion of the dryin chamber. Thus situated, the thermostat actuallyresponds to the temperature of the return and fresh air mixture suppliedto the chamber by fan 40, but it is to be understoodthat the thermostatmay be located at any desired point in the drying chamber or aircirculating system. By means of any desired and well known pneumatic orelectrical connection, diagrammatically indicated at 64, the thermostat53 controls the supply of gas to the burners. While suitable control maybe effected by modulating the supply of gas to the burners, and/or byrendering the burners serially operative and inoperative, it ispreferred to provide the gas lines 35 and 31 with valves 55 and 66,respectively. These valves are so arranged that when relatively littleheating is required, only the burners served by manifold 38 will beoperative, whereas the burners served by both gas supply manifolds willbe operative whenever more heating is required.

At the rear of the chamber 20, extending thereacross behind the web 23,is a steam chamber 61 of which at least the front wall 63 is formed ofmetal or other substance having a relatively high heat conductivity.Steam or water, preferably the latter, is supplied to the chamber 61under the control of a suitable valve 69 through supply pipe whichconnects with the lower portion of the chamber 61. Valve 69 may beregulated in any desired manner, and will be closed when the dryingapparatus is inoperative. Water supplied the temperature within thechamber 20 will be of the order of 500-1500 F. This rapid vaporizationabsorbs a considerable amount of heat and thus serves to cool the web,which tends to be blown against the wall 58 by the air discharged frompassages 21. Steam thus generated within chamber 61 is relievedtherefrom through pipe 1|, which is preferably provided with a reliefbranch 12, equipped with a suitable pressure relief valve 13 to preventthe pressure in chamber 61 from rising above a predetermined point. Thesteam delivered through pipe 1| is preferably controlled by a suitablevalve 14. It .will be understood that if steam is supplied to thechamber 51, this steam will be further heated and thus efiectsubstantial cooling of the web, although the cooling effect will be lessthan if water were employed.

A branch pipe 15 delivers steamfrom pipe 1! to a preheating roller 15over which the web ma.-

terial passes enroute to the drying chamber.

Steam condensate is relieved from the, roller 16 through drainconnection 11, preferably equipped with a steam trap 18. As illustrated,the preheating roller actuates the speed responsive control device 51,but it is to be understood that the latter may be actuated in any othersuitable manner.

A plurality of steam nozzles or sprays 19, fed by pipe 1!, are arrangedon opposite sides of the web proximate the outlet opening 24. Thus,moisture is returned to the web material so that it is within thechamber 51 quickly vaporizes, since The steam remaining in pipe H isrouted through a superheating coil 80, situated in the drying chamber20. As illustrated, the coil is positioned toward the front of thechamber, 20, Where it is subject to the action of the relatively hot airsupplied to chamber 20 by fan 40. Since this air has a relatively hightemperature, the steam in coil 80 is considerably superheated, to atemperature of the order of 500-800 F.

superheated steam from coil 80 is then supplied to manifold 8|, servinga plurality of steam nozzles or sprays 82 arranged in the path of thehot air discharged through supply passages 21 and extending across thewidth of the drying chamber. As this steam is mixed with the exceedinglyhot air passing through passages 21, there is no opportunity for it tocondense. However, since the temperature of the web material never,under normal operating conditions, rises above approximately 200 degreesF., condensation occurs as the steam vapor impinges upon the webmaterial. This is especially true of the entering end of the dryingchamber 20, since the web material normally enters at a temperature of70-80 F. The condensation which does occur, however, is exceedinglyfine, and does not harm the web material. On the contrary, it aids inbringing about effective drying at lower temperatures than couldotherwise be successfully employed since the fine deposit of moisturesubstantially increases the efficiency of heat transfer. The steamremaining in the air is withdrawn with the return air, so that the majorportion of it is returned with the return air delivered to the chamber20 by the fan 40. In practise, the air is provided with as much steam asit can contain without adversely affecting the oxygen requirements ofthe burners. By recirculating both steam and hot air to the greatestextent feasible, substantial reduction in operating costs are achieved,it being understood, however, that a portion of the circulated air andsteam must be withdrawn and replaced by fresh air and steam in order tomaintain such a vapor or fume dilution as will permit effective dryingaction.

It will be appreciated that by arranging the burners near the web but ata sufficient distance therefrom so that the flames and web are never incontact, the dangers of subjecting web ma terials to direct flames areobviated, while at the same time the heat of the flames is fullyutilized, without any appreciable loss, for drying purposes. Moreover,while avoiding the use of direct flames for drying,-there has beenprovided a system in which effective drying temperatures can be producedalmost instantaneously.

Fig. 4 illustrates a modified arrangement for cooling the web, in whichther is provided a partition 83, spaced from the rear of the chamber 20to provide a plenum chamber 84, and provided with a plurality ofapertures 85, preferably in the form of slots extending throughout thewidth of chamber 20. A fan 86 draws relatively cool air from any desiredsource, such as the ambient atmosphere or the outdoors, and suppliesthis air to plenum chamber 84. This air is discharged therefrom throughapertures 85 against the rear of web 23, and thus cools the web so as toprevent scorching or burning thereof. The air thus discharged iswithdrawn from chamber 20 with the air delivered through supply passages21. Since this modification of the invention contemplates theelimination of steam chamber 61, steam is supplied to th pipe H from anysuitable external source.

Figs. 5 and 6 illustrate a modified steam generating and/or superheatingdevice arranged for cooling the web, as an alternative for theconstruction illustrated in Figs. 2 and 3. As shown, a supply header 8!is supplied with water or steam by supply pipe 88. A plurality of tubes8! connect the header 81 with header 90, arranged at the opposite end ofdrying chamber 2|).

terial, means for circulating through said air supply passageways airand products of combustion withdrawn through said port means and freshair in controlled proportions, and means for exhausting from theapparatus air and products of combustion which have contacted with saidmaterial and are not recirculated to said air supply passages, dampermeans for regulating the exhaust of air and products of combustion, theinflow of fresh air and the recirculation of air and products ofcombustion, means for detecting changes in the speed of web travelthrough the casing and means responsive theretofor controlling theproportions of fresh air and returning air and products of combustion.

2. Ina drying apparatus of the character described, a casing forming adrying chamber,

, delivery, return air port means adapted to receive air and products ofcombustion which have contacted with said material, means forcirculating through said air supply passageways air and Steam generatedand/or superheated within the tubes 89 is delivered from header 9!! topipe II, for utilization as set forth above.

If desired, the burners may be supplied with a combustible mixture offuel and air, rather than with fuel only, as described above. The supplyof such a combustible mixture to the burners renders the burneroperation independent of the oxygen content of the air circulatedthrough the drying chamber, and hence the steam content of thecirculated air may be substantially higher than where the oxygen of thecirculated air is required to support combustion of the burners.

Since many changes may be made in the invention without departing fromthe scope. thereof, it is intended that all matter set forth in theabove description and accompanying drawings be regarded as illustrativeand not in a limiting sense.

I claim:

1. In a drying apparatus of the character described for drying inked webmaterial, a casing forming a drying chamber, means for passing throughsaid casing a web to be dried, at "plurality of air supply passagewayswithin said casing adapted to deliver air to said material at aplurality of points, shielded burner means arranged in said air supplypassageways and spaced from said points of air delivery, return air portmeans adapted to receive air and products of combustion which havecontacted with said maproducts of combustion withdrawn through said portmeans and fresh air in controlled proportions, means for exhausting fromthe apparatus air and products of combustion which have contacted withsaid material and are not recirculated to said air supply passages,damper means for regulating the exhaust of air and products ofcombustion, the inflow of fresh air and the recirculation of air andproducts of combustion, means for detecting changes in the speed oftravel of said material through the casing and means responsive theretofor controlling the proportions of return air and products of combustionand fresh air circulated through said air supply passages.

3. In a drying apparatus of the character described, a casing forming adrying chamber, means for passing through said casing material to bedried, a plurality of air supply passagewayswithin said casing adaptedto deliver air to said material at a plurality of points, shieldedburner means arranged in said air supply passageways and spaced fromsaidpoints of air delivery, return air port means adapted to receive airand products of combustion which have contacted with said material,means for circulating through said air supply passageways air andproducts of combustion withdrawn through said port means and fresh airin controlled proportions, means for exhausting from the apparatus airand products of combustion which have contacted with said material andare not recirculated to said air supply passages, damper means forregulating the exhaust of air and products of combustion, the inflow offresh air and the recirculation of air and products of combustion andmeans for detecting changes in the speed of travel of said materialthrough said casing for controlling the proportions of return air andproducts of combustion and fresh air circulated through said air supplypassageways and adapted to prevent the recirculation of return air andproducts of combustion whenever movement of said material through saidcasing is interrupted, whereby fresh air only is then supplied to saidmaterial to avoid overheating thereof.

4. In an apparatus of the character described for drying inked webmaterial, a casing forming a drying chamber, means for passing throughsaid chamber a web to be dried, means for discharging hot air andproducts of combustion against one side of said web, fluid containingmeans within said casing on the opposite side of said web and proximatethe same, means for supplying fluid to said containing means, theabsorption of heat by fluid at a desired temperature in said containingmeans serving to cool said web, means for delivering fluid in gaseousform from said containing means, and means for discharging said gaseousfluid against said flrst mentioned side of said web.-

5, In an apparatus of the character described for drying inked webmaterialfa casing forming a drying chamber, means for passing throughsaid chamber a web to be 'dried, means for discharging hot air andproducts of combustion against one side of said web, fluid containinmeans within said casing on the opposite side of said web and proximatethe same, means for supplying fluid to said containing means, theabsorption of heat by fluid at a desired temperature in said containingmeans serving to cool said web, means for delivering fluid in gaseousform from said containing means, means for discharging said gaseousfluid against said flrst mentioned side of said web, means forrecirculating to said casing air and gaseous fluid withdrawn therefromafter contact with said web, and a superheater connected between saidfluid containing means and said fluid discharging means and positionedin the path of said recirculated air an gaseous fluid.

6. In an apparatus of the character described, a casing forming a dryingchamber, means for passing through said chamber an inked web to bedried, means for discharging hot air and products of combustion againstone side of said web, fluid containing means within said casing on theopposite side of said web and proximate the same, means for supplyingfluid to said containing means, the absorption of heat by fluid at adesired temperature in said containing means serving to cool said web,means for delivering fluid in gaseous form from said containing means,means for discharging said gaseous fluid against said first mentionedside of said web, means for recirculating to said casing air and gaseousfluid withdrawn therefrom after contact with said web, and a superheaterconnected between said fluid containing means and said fluid dischargingmeans and positioned in said casing.

BERNARD OF'FEN.

CERTIFICATE OF C0 RRECTION Patent No. 2,297,31h. September 29, 19 42.

BERNARD OFFEN It is hereby certified that error appears in the printedspecification of the above numberedpatent requiring c'orrection asiollows: Page 2, first column, line 2, for"Fig. '2" read --Figs. 2 and5"; line 6, for "Fig. 1" read Figs. land 2-.-; page 1., first -c olumn,line 70, for "material" read -w eb-- line 75, strike out "1115-"; andsecond column, line' 1, for the le tezflal" read web--; line7, for"material" read --web-; p g 5,.second column, Iine 6, for "an" read-and--; and that the said Letters Patent should be read with thiscorrection therein that the same may conform'to the record'of the casein the Patent Office.

Signed and sealed this 12th day of January, A. D. 1915.

Henry Van Arsdale, -(Sea1) Acting Commissioner of Patents.

